1. Field of the Invention
The present invention relates to an integral rotor shaft and generator with bearing support, and more specifically to a small gas turbine engine with an integral electric generator and bearing support.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A Prior Art rotor shaft and generator unit is shown in FIG. 1. An electric generator includes a rotor or armature 114 and a stationary field coil 112. The armature 114 is rotatably connected to a rotor shaft 102 at the proximal or inner ends of the armature 114 and the shaft 102. The armature 114 is supported for rotation by a distal or forward end bearing 104 and a proximal or of end bearing 106. The rotor shaft 102 is supported for rotation by a proximal or forward end bearing 108 and a distal or aft end bearing 110. The proximal bearings are located on the proximal ends or adjacent ends of the rotor shaft 102 and the armature 114 while the distal ends are on the opposite ends. At high rotational speeds, the rotor shaft 102 will flex at points between the bearings due to the rotor dynamics of the shaft. If the electric generator is coupled to the rotor shaft 102 as in the FIG. 1 structure, the proximal or forward end of the shaft will flex in the radial direction and cause the generator to vibrate excessively. What is needed in the Prior Art of rotor shafts that drive an electric generator is a way to de-couple the generator from the rotor dynamics of the rotor shaft.
In the field of gas turbine engines, the engine includes a compressor driven by a rotor shaft to compress air, a combustor to burn the compressed air with a fuel to produce a hit gas stream, and a turbine connected to the rotor shaft to convert a portion of the hot gas stream to mechanical energy to drive the compressor. It is known in the prior art of gas turbine engines to connect an electric generator to the gas turbine engine in order to use the mechanical power from the rotor shaft to drive the generator and produce electric power for use in the engine. Small gas turbine engines operate at higher rotational speeds due to the smaller diameter size of the engine. Thus, the rotor dynamics of the engine are significant design problems.
U.S. Pat. No. 5,376,827 issued to Hines on Dec. 27, 1994 and entitled INTEGRATED TURBINE-GENERATOR discloses an integrated turbine and generator with dual rotor having a first electric generator connected to the outer rotor and a second electric generator connected to the inner rotor. The second electric generator is connected directly to the inner rotor shaft at a location downstream from the turbine section. Hines et al discloses that a conventional roller bearing supports the output shaft of the inner rotor.
In a small gas turbine engine, the rotor shaft rotates at a higher speed than does a larger gas turbine engine. If a small gas turbine engine was to connect a generator directly to the shaft as in the Hines patent above, the rotor dynamics of the rotor shaft would be so large that the generator would be affected as well. The part of the shaft extending past the bearing 66 would vibrate too much that the generator would suffer from the vibrations. It is thus necessary to isolate the rotor dynamics of the shaft from the generator.
An object of the present invention is to provide for an electric generator to be de-coupled the rotor dynamics of the shaft that drives the generator.
Another object of the present invention is to reduce the weight of the electric generator and rotor shaft assembly by reducing the number of parts.
Another object of the present invention is to provide for a small gas turbine engine with an electric generator that can be easily installed or removed from the rotor shaft.
Another object of the present invention is to provide for a small gas turbine engine with an electric generator in which the generator is de-coupled from the rotor dynamics of the rotor shaft.
Another object of the present invention is to reduce the weight of a small gas turbine engine.
These objects and others will become apparent from the detailed description of the invention that follows.